Wheelchair wheel lock

ABSTRACT

A wheelchair wheel locking assembly comprises a first and a second displaceable wheel-engaging member, having a substantially continuously flexible linkage operably connecting the first and second wheel-engaging members. In the event the continuously flexible linkage is severed, the first wheel stop may continue to be operated by the actuating lever. A wheel-contacting surface of the wheel-engaging member may include a recess for engaging a portion of a wheel in an interference fit. A wheelchair comprising the wheel locking mechanism of the invention is also provided.

This application claims the benefit of priority in U.S. ProvisionalPatent Application Ser. Nos. 60/344,612, filed Dec. 26, 2001, and60/409,461, filed Sep. 10, 2002, both of which are incorporated hereinby reference, and is a continuation of U.S. patent application Ser. No.10/328,780, filed on Dec. 23, 2002, the entirety of which is alsoincorporated herein by reference.

FIELD OF THE INVENTION

This invention relates generally to the field of wheel lockingmechanisms for wheelchairs. In particular, the present invention relatesto a wheelchair lock adapted for use by individuals suffering fromgreater weakness in one hemisphere of the body. The present inventionrelates further to an improved wheel-contacting surface for a wheellock, providing enhanced wheel locking power without necessitating useof additional force.

BACKGROUND OF THE INVENTION

It is known to provide wheelchairs with mechanisms for locking thewheels thereof, preventing the wheelchairs from traveling except at theurging of the user. Standard wheelchair locks must be operated from bothsides of the chair, that is, the left wheel must be locked from the leftside, and the right wheel must be locked from the right side. However,often individuals requiring wheelchairs suffer from greater weakness inone side of the body than the other, such as for example stroke victims.Such persons must either reach across their body with the stronger armand hand to operate the opposite wheel lock, or require assistance fromanother person.

There have been attempts to address this deficiency of conventionalwheel locks. For example, U.S. Pat. No. 4,809,818 to Leggett et al.provides a dual braking structure consisting of a rod 14 attached to afirst wheel lock or brake, a center section 46; and a left rod 24attached to a second wheel lock. Thus, both brakes may be operated byactuating either brake. Center section 46 allows left and right rods 14,24 to be folded relative to one another when the wheelchair is folded.

U.S. Pat. No. 6,443,268 to Dearth et al. provides a similar assembly forlinking operation of two wheelchair locks or brakes. A crossmember 38comprising paired segments 42 pivotally coupled at their interior endsis connected to paired wheelchair brakes at the exterior ends of pairedsegments 42. Accordingly, operation of both wheelchair brakes may beaccomplished by actuating either brake. Because of the central pivotingcoupling, crossmember 38 may be folded when the wheelchair is folded.

These devices appear generally effective for their intended purpose.However, significant improvements are possible. Use of a bar or rod tolink paired wheelchair brakes or wheel locks adds weight to the chair,particularly when a sufficiently thick material is used to prevent thetwisting or torsion inherent in applying a force to a single end of abar or rod. Particularly in the case of a weakened user of the chair,any savings in weight is advantageous in terms of user comfort andconvenience. This extends to the comfort and convenience of personsassisting the wheelchair user.

The stopping power of a conventional wheel lock or wheel strike isprovided by frictional force. Therefore, to be effective a wheel lockmust contact a wheelchair wheel with the required amount of force tosubstantially prevent rotation thereof. This force is provided inresponse to an actuating force provided by the user. In order toincrease stopping power, a conventional wheel lock must be caused toengage the wheelchair wheel with increased force. Because the wheelchairuser is often relatively weakened, application of additional force maybe difficult. Further, materials from which wheelchair parts such aswheelchair locks are constructed have a finite strength and resistanceto shear forces, and in extreme conditions may break in response to theapplied force. It is therefore desirable to find means for improving thestopping capability of a wheel lock without necessitating application ofincreased force.

Therefore, a need in the art exists for a wheel locking mechanism whichis easy to operate for persons with partial or total immobility orweakness in one side of their body. Such a wheel locking mechanismshould preferably be adaptable for affixation or retrofitting to anystandard wheelchair design.

SUMMARY OF THE INVENTION

It is known to provide a wheelchair for transporting fully or partiallydisabled persons, having a frame, a seat and back supported on theframe, and at least two primary drive wheels. When the wheelchair is atrest, it is often desirable to lock the wheels thereof to preventinadvertent travel of the chair, either with or without an occupant. Forexample, when the occupant is exiting or entering the chair, such as toor from a bed, movement of the wheelchair is preferably restricted toprovide a secure platform for the user. Accordingly, in one aspect, thepresent invention provides a wheel locking assembly for substantiallypreventing rotation of a wheelchair wheel or tire about its axis.Advantageously, the wheel locking assembly of the invention allows theuser to lock both wheels of the wheelchair from a single side of thechair, rather than requiring the user to access separate lockingmechanisms on opposed sides of the chair as is necessary in conventionalwheelchair wheel lock designs. It will be appreciated that this featureprovides significant advantages for users having a increased weakness ina particular hemisphere of the body, such as is common for strokevictims.

In one aspect, the present invention provides a wheel locking assembly,comprising a first and a second displaceable wheel-engaging member andan actuator operably connected to the first displaceable wheel-engagingmember. A substantially continuously flexible linkage operably connectsthe first and second displaceable wheel-engaging members, wherebyactuating the actuator concurrently displaces the first and secondwheel-engaging members. It will be appreciated by the skilled artisan,and further explained in greater detail herein, that the wheel lockingassembly is configured whereby the actuator remains operably connectedto the first wheel-engaging member if the continuously flexible linkageconnecting the first and second wheel-engaging members is severed.

Conventional wheelchair wheels include a ground-engaging portion,typically fabricated of a resilient material such as rubber. To beeffective for their intended purpose, wheelchair wheel locks mustcontact this ground-engaging portion with sufficient force to preventrotation of the wheel. This usually causes the wheel-contacting surfaceof the wheel-engaging member to partially indent the ground-engagingportion, thereby reducing the likelihood of rotation. However, withconventional wheelchair wheel locks there is still a possibility ofslippage.

To address this problem, the wheel-engaging member of the invention mayinclude a wheel-contacting surface having a recess for engaging aportion of a wheel in an interference fit. The wheel-contacting surfaceof the present invention partially indents the resilient ground-engagingportion of a wheelchair wheel as is known in the art for conventionalwheel locks. Additionally, as the wheel-contacting surface is biasedagainst the ground-engaging portion of the wheel, a portion of theground-engaging portion of the wheel protrudes into the cutout to forman interference fit, thereby significantly improving the stopping orgripping force on the wheel in comparison to a conventional wheel lockupon application of a similar biasing force. The recess may be of anydimensions and define any shape suitable for providing a space intowhich the wheel ground-engaging surface may protrude. In one embodiment,the recess is substantially concave.

The substantially continuously flexible linkage comprises a flexiblemember having a first end operably connected to the first wheel-engagingmember and a second end operably connected to the second wheel-engagingmember. In one embodiment, the continuously flexible linkage is apush-pull cable having a substantially flexible outer sheath surroundinga wire. However, it will be appreciated that other configurations arepossible, such as a wire threaded through a series of eyelets affixed tothe wheelchair to interconnect the first and second wheel-engagingmembers.

In another aspect, a wheel locking assembly is provided, comprising atleast one displaceable wheel-engaging member and an actuator operablyconnected to the wheel-engaging member. The wheel-engaging memberincludes a wheel-contacting surface having a recess for engaging aportion of a wheel in an interference fit. The recess may besubstantially concave. In one embodiment, first and a seconddisplaceable wheel-engaging members may be provided, and the wheellocking assembly may include a substantially continuously flexiblelinkage operably connecting the first and second displaceablewheel-engaging members.

In yet another aspect, a wheelchair is provided in accordance with theteachings of the present invention, comprising a frame, a seat, at leasttwo wheels, and a wheel locking assembly. The wheel locking assemblycomprises a first and a second displaceable wheel-engaging member heldat a spaced distance from the wheels, with a substantially continuouslyflexible linkage operably connecting the first and second displaceablewheel-engaging members. An actuator is operably connected to the firstdisplaceable wheel-engaging member, and it will be appreciated from theforegoing discussion that actuating the actuator concurrently displacesthe first and second wheel-engaging members. The actuator remainsoperably connected to the first wheel-engaging member if thesubstantially continuously flexible linkage connecting the first andsecond wheel-engaging members is severed or otherwise damaged.

The substantially continuously flexible linkage comprises a flexiblemember having a first end operably connected to the first wheel-engagingmember and a second end operably connected to the second wheel-engagingmember. In one embodiment, the linkage is a push-pull cable as describedabove. As also described above, a wheel-contacting surface of thewheel-engaging member includes a recess for engaging a portion of thewheel in an interference fit, the recess being substantially concave inone embodiment.

In still yet another aspect of the present invention, a wheel stop isprovided, comprising a wheel-engaging member having a wheel-contactingsurface. The wheel-contacting surface includes a recess for engaging aportion of a wheel in an interference fit, which may be substantiallyconcave.

Still other objects of the present invention will become apparent tothose skilled in this art from the following description wherein thereis shown and described a preferred embodiment of this invention, simplyby way of illustration of one of the modes best suited to carry out theinvention. As it will be realized, the invention is capable of otherdifferent embodiments and its several details are capable ofmodification in various, obvious aspects all without departing from theinvention. Accordingly, the drawings and descriptions will be regardedas illustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWING

The accompanying drawing incorporated in and forming a part of thespecification illustrate several aspects of the present invention and,together with the description, serve to explain the principles of theinvention. In the drawing:

FIG. 1 is a perspective view of one embodiment of the wheel lockingassembly of the present invention, installed on a conventionalwheelchair;

FIG. 2 is a side view of a first wheel-engaging member in accordancewith the present invention;

FIG. 3 is a side view of a second wheel-engaging member in accordancewith the present invention; and

FIG. 4 is a perspective view of a dual-lever embodiment of the wheellocking assembly of the present invention.

Reference will now be made in detail to the presently preferredembodiment of the invention, an example of which is illustrated in theaccompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

As best seen in FIG. 1 appended hereto, the wheel locking assembly 10 ofthe present invention may be mounted to a wheelchair (shown in brokenlines for convenience) having a frame, a seat and back attached to theframe, and at least two primary drive wheels. Of course, the wheellocking assembly 10 of this invention will be mounted to the wheelchairsuch that the wheel locks are in spaced relation to the primary drivewheels to allow locking thereof. The wheel locking assembly 10 of theinvention may comprise a first wheel stop 20, a second wheel stop 22,and a substantially continuously flexible linkage 24 operably connectingthe wheel stops 20, 22. Wheel stops 20, 22 may be fabricated of anysuitably durable, corrosion-resistant material commonly used tofabricate wheelchair wheel stops, including but not limited to metalssuch as aluminum and stainless steel, and suitably durable plastics

FIG. 4 is a perspective view of a dual-lever embodiment of the wheellocking assembly of the present invention.

Reference will now be made in detail to the presently preferredembodiment of the invention, an example of which is illustrated in theaccompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

As best seen in FIG. 1 appended hereto, the wheel locking assembly 10 ofthe present invention may be mounted to a wheelchair (shown in brokenlines for convenience) having a frame, a seat and back attached to theframe, and at least two primary drive wheels. Of course, the wheellocking assembly 10 of this invention will be mounted to the wheelchairsuch that the wheel locks are in spaced relation to the primary drivewheels to allow locking thereof. The wheel locking assembly 10 of theinvention may comprise a first wheel stop 20, a second wheel stop 22,and a substantially continuously flexible linkage 24 operably connectingthe wheel stops 20, 22. Wheel stops 20, 22 may be fabricated of anysuitably durable, corrosion-resistant material commonly used tofabricate wheelchair wheel stops, including but not limited to metalssuch as aluminum and stainless steel, and suitably durable plastics orpolymers.

Referring to FIG. 2, the first wheel stop 20 comprises a mounting blockor bracket 25 for mounting same to a wheelchair frame, a displaceablewheel-engaging member 26, and an actuator, in this embodiment actuatinglever 28. It should be appreciated that mounting block or bracket 25 maybe fabricated to any desired configuration for mounting to a wheelchairin accordance with the manufacture of the wheelchair frame, such as bythreaded nuts and bolts, clamps, and the like. Thus, the wheel lockingmechanism 10 of the present invention may be incorporated into thewheelchair during manufacture, or may be retrofitted to any existingmanufacture of wheelchair. Mounting block or bracket 25 may also beconfigured to mount to either side (left or right) of the wheelchair.The advantage of this feature will be described in greater detail below.

The displaceable wheel engaging member 26 includes a top end 30, acentral pivot point 32, and a bottom end 34 having a wheel strike 36with a wheel-contacting surface 38 thereon. It will be appreciated thatthe wheel-strike 36 may be integral to the wheel-engaging member 26 (seeFIG. 4), or may be attached thereto by any desired means, such as athreaded nut 39 and bolt 40. The mounting bracket 25 further includes asupport 42 connected thereto, such as by threaded nuts and boltassemblies 44. It is also possible to fabricate support 42 as anintegral member of mounting bracket 25.

In the depicted embodiment, wheel strike 36 includes a wheel-contactingsurface 38 having a recess 46 therein for engaging the wheelchair wheelor tire. It will be appreciated that the wheel-contacting surface 38 ofthe present invention partially indents a resilient ground-engagingportion of a wheelchair wheel (shown in phantom for convenience in FIGS.2 and 3). Advantageously, as the wheel-contacting surface 38 is biasedagainst the ground-engaging portion of the wheel with the desired force,a portion of the resilient material of the ground-engaging portion ofthe wheel protrudes into the recess 46, thereby creating an interferencefit and significantly improving the stopping or locking force placed onthe wheel in comparison to conventional smooth, knurled, or ridged wheellocks. The recess 46 may be of any dimensions suitable for providing aspace into which the wheel ground-engaging surface may protrude. In theembodiment shown in FIGS. 2-4, the wheel-contacting surface 38 recess 46is substantially concave.

The actuating lever 28 is operably connected to the displaceablewheel-engaging member 26, depicted in FIG. 2 by linkage 48. However, itwill be appreciated that other suitable configurations for operablyconnecting actuating lever 28 to wheel-engaging member 26 are possible.For example, actuating lever 28 may simply be an integral extension ofwheel-engaging member 26, extending upwardly from top end 30 thereof. Asthe actuating lever 28 is biased in the direction of arrow A, linkage 48displaces the wheel-engaging member 26 about central pivot point 32,whereby wheel-contacting surface 38 is urged in the direction of arrow Bto contact the wheelchair wheel (shown in broken lines for convenience).

Substantially continuously flexible linkage 24 may be connected tosupport 42 by any suitable means. As shown in FIGS. 2 and 3,substantially continuously flexible linkage 24 may be a push-pull cableof a type known in the art, comprising a hollow sheath 50 having a wire52 slidably inserted in the interior of hollow sheath 50. Hollow sheath50 may be connected to support 42 by a threaded fitting 54, allowingeasy installation, removal, and replacement thereof. It will beappreciated that wire 52 may be fabricated of any suitable material,with only the limitation that it must be sufficiently strong to pull thewheel stops 20, 22 into contact with the wheelchair wheels with thedesired force to prevent rotation of the wheels, and to push the wheelstops 20,22 away from contact with the wheels to allow free rotationthereof.

A first end 56 of wire 52 is connected to top end 30 of wheel engagingmember 26, such as by a pivoting fitting 58. A threaded fitting 60allows tensioning or loosening of wire 52 as desired. It will beappreciated that in accordance with this configuration, when actuatinglever 28 is biased in direction A, top end 30 of wheel-engaging member26 biases wire 52 in the same direction.

As shown in FIG. 3, second wheel stop 22 may comprise a second mountingblock or bracket 25′, having a support 42′ connected thereto. Secondwheel stop 22 further includes a second displaceable wheel-engagingmember 62, having a first or displaceable end 64 connected to secondmounting bracket 25′ by any suitable means allowing pivoting thereof,and a second end 66 having a second wheel strike 36′ thereon. Secondmounting block or bracket 25′ may also be configured to mount to eithera left or a right side of the wheelchair. Second wheel strike 36′ may beintegral with second wheel-engaging member 62, or may be connectedthereto by threaded nuts and bolts (not shown). In the depictedembodiment, second wheel strike 36′ includes a wheel-engaging surface38′ having a recess 46′ therein.

Flexible linkage 24 connects to second wheel stop 62 at a second end 66thereof. Hollow sheath 50 is connected to support 42′ by any desiredmeans, such as a threaded linkage 54′. Second end 68 of wire 52 isconnected to second end 66 of wheel-engaging member 62 by any desiredmeans, such as a pivoting fitting 58′. This allows wire 52 to biaswheel-engaging member 62 in direction C, into contact with a wheelchairwheel, or to push wheel-engaging member 62 in direction D, away fromcontact therewith.

The operation of the wheel locking assembly 10 of the present inventionwill now be described. The wheel locking assembly 10 is mounted inposition on opposed sides of a wheelchair (see FIG. 1) using mountingbrackets 25, 25′, such that wheel-engaging members 26, 62 may bedisplaced into contact with the primary drive wheels of the chair. Tolock the wheels, actuating lever 28 is biased in direction A. Throughlinkage 48, first wheel-engaging member 26 pivots to push firstwheel-contacting surface 38 into locking contact with a correspondingwheelchair wheel, preventing rotation thereof. As the firstwheel-contacting surface 38 indents the resilient ground-engagingportion of the wheelchair wheel, a portion of the wheel protrudes intorecess 46, significantly enhancing the locking ability of the wheel stop20 without requiring application of any additional force.

Concurrently, top end 30 of first wheel-engaging member 26 is biased indirection A. Impelled by flexible linkage 24, the second wheel-engagingmember 62 pivots to move second wheel-contacting surface 38′ indirection C and into locking contact with the opposed wheelchair wheel.Biasing actuating lever 28 in the opposite direction B simultaneouslypulls first wheel-contacting surface 38 away from contact with thecorresponding wheelchair wheel, and pushes second wheel-contactingsurface 38′ away from contact with the opposed wheelchair wheel.

A feature of the wheel locking assembly 10 will become immediatelyapparent through the above description. When flexible linkage 24 isintact, both wheel stops 20, 22 may be simultaneously operated using asingle actuating lever 28 placed on a single side of a wheelchair.Recesses 46, 46′ on wheel-contacting surfaces 38, 38′ provide enhancedstopping power without requiring use of increased force, as described indetail above. This provides significant advantages to the user,particularly a user who suffers from greater weakness in a particularhemisphere of the body. By simply mounting the wheel locking assembly 10of this invention on a wheelchair such that actuating lever 28 ispositioned to be accessible to the user's stronger side, whether it bethe left or the right side, convenience and effectiveness are enhanced.

In the event that flexible linkage 24 is severed, a further feature ofthe invention is revealed. Notwithstanding that flexible linkage 24 mayhave been severed or otherwise damaged such that second wheel stop 22 isrendered inoperable, first wheel stop 20 may still be used to lock atleast one primary drive wheel of the wheelchair using actuating lever28. Accordingly, effectiveness of the wheel locking assembly 10 andconvenience to the user are further enhanced.

A further advantage is provided by use of flexible linkage 24. Manystandard wheelchairs are designed to be collapsed into a narrowconfiguration for ease of transport and storage. Standard linkages suchas connecting rods would deprive the user of the ability to collapse thewheelchair for transport, or in the alternative require removal of thewheel locking assembly 10 prior to collapsing the chair. In contrast,the flexible linkage 24 of the present invention has sufficientflexibility to bend when the wheelchair is collapsed, and to resume itsoriginal configuration when the wheelchair is reformed for use. Awheelchair fitted with the wheel locking assembly 10 of the presentinvention may therefore be collapsed and reformed without need ofremoval of the wheel stops, thereby increasing convenience andeffectiveness for the user and for persons assisting the user.

Of course, additional configurations of the wheel locking assembly 10 ofthis invention are possible which preserve the advantageous featuresthereof as described. Referring now to FIG. 4, a dual-lever wheel stop70 providing independent control of two wheel-engaging members is shown.Dual-lever wheel stop 70 includes a mounting bracket 25 and support 42substantially as described above. A displaceable first actuating lever72 is provided, operably connected to first wheel-engaging member 26through linkage 48. First actuating lever 72 operates firstwheel-engaging member 26 substantially as described above.

A displaceable second actuating lever 74 is also provided, which isoperably connected to a rocker arm 76 through a linkage 78. Rocker arm76 includes a top end 80 adapted to receive a first end 56 of wire 52 ofcontinuously flexible linkage 24 substantially as described above, forexample by a pivoting fitting 58 comprising a pin and clip. The opposedend of wire 52 (not shown) is operably connected to second wheel stop 22(not shown) substantially as described above.

Accordingly, it will be appreciated that control of both wheel stops 70,22 may be independently effected from a single side of a wheelchair. Inthe event that flexible linkage 24 is severed, first actuating lever 72may continue to effect locking of one wheelchair wheel, thus improvingthe effectiveness of the wheel locking assembly 10 of this invention.

The foregoing description of a preferred embodiment of the invention hasbeen presented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formdisclosed. Obvious modifications or variations are possible in light ofthe above teachings. The embodiment described was chosen to provide thebest illustration of the principles of the invention and its practicalapplication to thereby enable one of ordinary skill in the art toutilize the invention in various embodiments and with variousmodifications as are suited to the particular use contemplated. All suchmodifications and variations are within the scope of the invention asdetermined by the appended Claims when interpreted in accordance withthe breadth to which they are fairly, legally and equitably entitled.

1. A wheel locking assembly, comprising: a first and a seconddisplaceable wheel-engaging member; an actuator operably connected tothe first displaceable wheel-engaging member; and a substantiallycontinuously flexible linkage operably connecting the first and seconddisplaceable wheel-engaging members; whereby actuating the actuatorconcurrently displaces the first and second wheel-engaging members. 2.The wheel locking assembly of claim 1, wherein the actuator remainsoperably connected to the first wheel-engaging member if thecontinuously flexible linkage connecting the first and secondwheel-engaging members is severed.
 3. The wheel locking assembly ofclaim 1, wherein a wheel-contacting surface of the wheel-engaging memberincludes a recess for engaging a portion of a wheel in an interferencefit.
 4. The wheel locking assembly of claim 3, wherein the recess issubstantially concave.
 5. The wheel locking assembly of claim 1, whereinthe substantially continuously flexible linkage comprises a flexiblemember having a first end operably connected to the first wheel-engagingmember and a second end operably connected to the second wheel-engagingmember.
 6. The wheel locking assembly of claim 5, wherein thecontinuously flexible linkage is a push-pull cable having asubstantially flexible outer sheath surrounding a wire.
 7. A wheellocking assembly, comprising: at least one displaceable wheel-engagingmember; and an actuator operably connected to the wheel-engaging member;wherein the wheel-engaging member includes a wheel-contacting surfacehaving a recess for engaging a portion of a wheel in an interferencefit.
 8. The wheel locking assembly of claim 7, including a first and asecond displaceable wheel-engaging member and a substantiallycontinuously flexible linkage operably connecting the first and seconddisplaceable wheel-engaging members.
 9. The wheel locking assembly ofclaim 7, wherein the recess is substantially concave.
 10. A wheelchair,comprising; a frame; a seat; at least two wheels; and a wheel lockingassembly comprising a first and a second displaceable wheel-engagingmember, a substantially continuously flexible linkage operablyconnecting the first and second displaceable wheel-engaging members, andan actuator operably connected to the first displaceable wheel-engagingmember; whereby actuating the actuator concurrently displaces the firstand second wheel-engaging members.
 11. The wheelchair of claim 10,wherein the actuator remains operably connected to the firstwheel-engaging member if the substantially continuously flexible linkageconnecting the first and second wheel-engaging members is severed. 12.The wheelchair of claim 10, wherein a wheel-contacting surface of thewheel-engaging member includes a recess for engaging a portion of thewheel in an interference fit.
 13. The wheelchair of claim 12, whereinthe recess is substantially concave.
 14. The wheelchair of claim 10,wherein the substantially continuously flexible linkage comprises aflexible member having a first end operably connected to the firstwheel-engaging member and a second end operably connected to the secondwheel-engaging member.
 15. The wheelchair of claim 14, wherein thecontinuously flexible linkage is a push-pull cable having asubstantially flexible outer sheath surrounding a wire.
 16. A wheelstop, comprising a wheel-engaging member having a wheel-contactingsurface, wherein the wheel-contacting surface includes a recess forengaging a portion of a wheel in an interference fit.
 17. The wheel stopof claim 16, wherein the recess is substantially concave.